Cyclic Behavior of Square CFST Columns-Based Joint

This paper investigates the cyclic behavior of six square concrete-filled steel tube (CFST) columns that take the effect of width–thickness ratio (D/t = 30, 40, and 60), slenderness ratio (λ = 19.63 and 24.25), and axial force ratio (n = 0.6, 0.4, and 0.2) into consideration. The failure modes, hysteretic behavior, energy dissipation capacities, stiffness degradation, and ductility of these specimens have been discussed and studied. The results revealed that a bigger D/t could reduce the energy dissipation capacities and bearing capacities of the columns. With increasing λ, the energy dissipation capacities and bearing capacities of columns reduced, and the stiffness deteriorated rapidly. The axial force ratio could enhance the bearing capacities but weaken their energy dissipation capacities and stiffness. Calculation formulae for ultimate moment strength of square CFST columns were exhibited to compare to the test results.